Deadly flooding inundated parts of the Northeast, trapping people in their homes and killing at least one woman who was swept away by the fast-moving water. Rivers in Vermont rose quickly in the torrential rain on Monday to levels not seen since Hurricane Irene in 2011.
The climate crisis is stacking the deck in favor of more intense weather events like the heavy rain and flooding in the Northeast, said Michael E. Mann, a climate scientist and distinguished professor at the University of Pennsylvania.
There’s another, more surprising way that the climate crisis could be driving these extreme rainfall events, Mann said, and it’s something on the forefront of climate research: The jet stream could be getting “stuck” in positions that prolong these kinds of extreme events.
The jet stream is the fast-moving river of air high in the atmosphere that ushers weather systems across the globe. Importantly, it’s fueled by the extreme difference in temperature between the equator and the poles.
But the planet is not warming equally in all locations, Mann explained. The Arctic is warming much faster than the Lower 48, for example, which “reduces the temperature difference from the equator to the pole.”
Scientists suspect that this decrease in temperature difference is changing how the jet stream behaves.
“The jet stream basically stalls and those weather patterns remain in place — those high and low pressure centers remain in place,” Mann said. “And we’re seeing more of these sort of stuck, wavy jet stream patterns that are associated with these very persistent weather extremes, whether it’s the heat, drought, wildfire or the flooding events.”
As the Northeast is inundated with flooding rain, dangerous heat is threatening other parts of the world. Temperatures are soaring in the Southwest this week, where Phoenix could break its record for consecutive number of days above 110 degrees.
Meanwhile, the EU’s Copernicus Climate Change Service found that last month was the hottest June by a “substantial margin” above the previous record, which was set in 2019.
Given the exceptional heat, scientists are concerned that 2023 could be the hottest year on record.
Mann said that El Niño is “adding extra heat, extra fuel to the fire.” El Niño, which is a warm phenomenon in the Pacific Ocean, is combining with the climate crisis “and what you get is new record levels of heat at the planetary scale.”
But Mann said without the climate crisis, which is caused by burning fossil fuels, “we simply wouldn’t be seeing these extreme events.”
“Those are conspiring. They’re combining,” Mann said. “The steady warming combined with an El Niño; extreme weather events related to those changing jet stream conditions – it all comes together, if you will, in a perfect storm of consequences, which translates to truly devastating and deadly weather extremes that we’re dealing with here right now.”